Problem: $ { {-4} \times \left[\begin{array}{r}{0} \\ {-2} \\ {-1}\end{array}\right] = {?} } $
Explanation: To multiply a matrix by a number, multiply each item of the matrix by the number. ${\left[\begin{array}{r}{-4}\times{0} \\ {-4}\times{-2} \\ {-4}\times{-1}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{r}{0} \\ {8} \\ {4}\end{array}\right]}$